High HC & CO - at High RPM
This condition indicates abnormally high Carbon Monoxide and Hydrocarbons during cruise (2500 rpm).
POSSIBLE CAUSE ACTION
Electrical misfires Check ignition system
Vacuum leak Check vacuum lines and routing in
"Vacuum and Vapor Hose Routing"
in Emissions - Check intake manifold
and vacuum components
Faulty bowl vent/canister purge system Check Evaporative System in
"Testing Procedures" in Emissions
PCV malfunction Check PCV system in "Testing
Procedures" in Emissions
EGR malfunction Check EGR system in "Testing
Procedures" in Emissions
Restricted exhaust Check Catalytic Converter in
"Testing Procedures" in Emissions
Initial timing incorrect Check Ignition Timing in "Adjustment
Procedures" in Emissions
Fuel metering malfunction
Carbureted Check carburetor passages, bleeds
and restrictors - Internal leaks,
float level, metering rods and gaskets
Replace or rebuild if faults are found
Fuel Injected Check fuel pressure
Perform injector balance test
Inspect regulator operation
(check vacuum line and return hose),
Service Fuel Injectors (Pressure cleaner)